As part of the "Air Engine Project" JDS Cycle donated an old beat up Honda that I could bolt the engine into.  Turns out the bike was a 1973 Honda ST-90 - the very first of only three years of production for this particular model.  The bike was in rough shape having been sitting outside in the elements for many years, however it was complete except for the carburetor - it even had both keys!  I couldn't bring myself to do anything less than restore it.  I strapped it to a trailer and brought it over to my buddy John's place to work on during lunch now that the CRF50 conversion was completed.  Note the funkadelic paint job!

So, as with any quality restoration, begin by taking everything apart. Cables, seat, fenders, exhaust, headlight, wiring...

... engine, handlebars...

...wheels, shocks, forks, swing arm, triple trees...

...until you're left with nothing but a garage full of miscellaneous parts.

Next is to turn to the various parts that need attention.  We started with some polishing - here are the before/after pics of various aluminum parts.

Next is the saddle.  The original cover is removed, the steel base is bead-blasted and repainted gloss black. The foam is in good shape, so no repairs are needed there.

Next the edges of the seat pan need to be softened so they don't cut through the seat cover.  The factory originally used an edge protector, but there's no beating a couple of layers of duct tape!

Next, the replacement seat cover is stretched over the foam starting at the front, then back, then sides.

The only badge on the bike is on the exhaust heat shield. The old paint and decals are stripped off to begin. Then, the entire piece is painted gloss black. After the paint is dry, the entire piece is masked.  Then, the "90" is cut out with a razor. The piece is painted white and re-masked. Next the "ST" is cutout and the piece is painted red. Finally the masking is removed.

After the paint is fully dry, the paint is removed from the raised edges and minor touching up is performed.

The ST-90s have the advantage over the more popular "Trail 70s" in that they are street legal. Unfortunately, this bike does not have a title. So, once again I turn to eBay and find a frame & title for sale and buy it for $100. The frame is cleaned, decals are removed, and is prepped for paint. Note how much the paint has faded over the years.

Some chips/scratches are feathered out.

Others are filled.

Rust is removed with phosphoric acid and the edges are feathered.

Finally, the entire frame is primed and ready for paint.

24 hours later, it's ready for the finish coat.  I was going to paint it with a high-quality automotive base coat/clear coat, but decided on rattle can - if it looks too good, it won't look authentic!

I have to say, it came better than I expected! Really happy with the results.

The carburetor is taken completely apart...

... and cleaned in an ultrasonic cleaner.

Afterwards, it is reassembled with all new gaskets.

Now that the bead-blasting is complete, it's time to refinish the parts.  Honda used several finishes on the 1973 ST90 - satin black, gloss black, and silver metallic.  In addition, most unfinished parts were zinc plated to prevent corrosion. Lastly, many of the brackets and fenders were chrome plated.

The existing chrome was not too bad once it was bead-blasted and polished.  There are minor pits and a couple of dings, but for now they will have to do.  At some point in the future I will have the chrome parts re-plated.  To protect them, I clear-coated all the chrome parts.

I painted the silver metallic and gloss black parts in John's garage.

The satin black parts I handled at home.

The engine had a really bad black paint job when I got it.  It was peeling badly and needed to be stripped off.  I plugged the intake and exhaust ports with a pair of John's old socks and bead blasted all the paint off.  I removed the points and stator covers to polish and make new gaskets.  They didn't come nearly as nice as the sprocket cover, though.

To make new gaskets, you basically trace the outline of the part onto the appropriate gasket material - in this case, we will need paper gaskets.

Once you cut out the outside, you press the gasket onto the part rubbing your finger around the inside edge to leave an impression.  Cut along the impression lines with an exacto knife and cut the holes for the fasteners. 

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That about does it for the refinishing work.  Now the fun begins - reassembly!  Start with the main wiring harness.  At one end are the connectors that are made in the headlight housing and ignition switch, the other end contains the wiring for the ignition system and rear lighting.  I also installed the molding on the upper seam (I couldn't resist).

Here's the bearings for the steering head - this is really nostalgic for me; the last time I worked with loose bearings like this was when I was a kid taking apart bicycles.  The trick to working with these types of bearings is the liberal use of grease. The race is greased up and the bearings are pressed into place.  The top is easy, the bottom is a little more challenging as gravity is working against you.

After the triple-trees are installed, the forks, handlebars, headlight bucket, etc. are installed.  Motorcycle manufactures utilize the space in the headlight bucket for making connections to the main wiring harness for things like turn signals, switches, horn, etc.

On this model, the other end of the main harness is connected to the rear components under the seat - the battery, rectifier, tail lamp, rear signals, and ignition system.  Also, the gas tank is under here as well.

After all the connections are complete, the electrical system can be tested. 

The engine is basically attached to the frame with three bolts.  The frame is not hard to handle with one person, but once the engine is attached, it's going to need two people to manage.  Here's a shot of the carburetor installed.

Next comes the new decals - believe it or not they are pretty much all available in the aftermarket.

The wheels are another story - note to self: allow 8 to 12 weeks to get anything from Thailand.

I had never laced motorcycle wheels before but I have done bicycle wheels as a kid.  It took me two tries to get them right, but it turned out great.  Truing wasn't too bad because the rims are very rigid - unlike bicycle rims.  Here are shots of my first attempt.  Off to a good start...

...and then things get bad...

 It looks correct, but it's not - the cross spokes are not in the correct place which makes them too long to tighten.  Here they are laced correctly.

Here she is - finally finished! The title work and registration is done, so she's officially street-legal (although I wouldn't take her out on the highway!)